Polycrystalline diamond (PCD) material comprises a mass of inter-grown diamond grains and interstices between the diamond grains. PCD may be made by subjecting an aggregated mass of diamond grains to a high pressure and temperature in the presence of a sintering aid such as cobalt, which may promote the inter-growth of diamond grains. The sintering aid may also be referred to as a catalyst material for diamond. Interstices within the sintered PCD material may be wholly or partially filled with residual catalyst material. PCD may be formed on a cobalt-cemented tungsten carbide substrate, which may provide a source of cobalt catalyst material for the PCD.
PCD material may be used in a wide variety of tools for cutting, machining, drilling or degrading hard or abrasive materials such as rock, metal, ceramics, composites and wood-containing materials. For example, tool inserts comprising PCD material are widely used within drill bits used for boring into the earth in the oil and gas drilling industry. In many of these applications, the temperature of the PCD material may become elevated as it engages rock or other workpiece or body with high energy. Unfortunately, mechanical properties of PCD material such as abrasion resistance, hardness and strength tend to deteriorate at elevated temperatures, which may be promoted by the residual catalyst material within it.
Akaishi et al. disclose in the Material Science and Engineering A (1988), volume 05/106, numbers 1 and 2, pages 517 to 523, a well-sintered diamond with a fine-grained homogeneous microstructure, which was synthesised at 7.7 GPa and 2,000 degrees centigrade when diamond powder with 1 to 5 volume percent Co or Ni additive was used as the starting material.
European patent publication number EP 1 931 594 discloses a method for producing a polycrystalline diamond (PCD) body with an arithmetic mean as-sintered grain size less than 1 micron, wherein the catalyst metal comprises an iron group metal such as cobalt and the sintering pressure is between about 2.0 GPa and 7.0 GPa.
United States patent application publication number 2005/0133277 discloses PCD made using a sintering pressure and temperature at 65 kbar and 1,400 degrees centigrade.
There is a need for polycrystalline diamond material having enhanced abrasion resistance.